Use of a flexible sleeve in the cementation of boreholes



Aug. 19, 1952 A. B. HILDEBRANDT USE OF A FLEXIBLE SLEEVE IN THE CEMENTAT ION OF BOREHOLES Filed Sept. 17; 1947 e m s A C LAP FED sHoE.

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Patented Aug. 19, 1952 USE OF A FLEIHBLE SLEEVE IN THE CEMENTATION OF BOREHOLES Alexander B. Hildebrandt, Tulsa, Okla., assignor to Standard Oil Development Company, a corporation of Delaware Application September 17, 1947, SerialNo. 774,649

1 Claim. (01. 1661) The present invention is concerned with an improved process for preparing bore holes for the production of oil. The invention is more particularly concerned with apparatus for securing an ing containing a conventional shoe. Figure 1 also illustrates-my sleeve or skirt device which is attached to .the lower end of thecasing. Figure '2 is a top'cross-sectional view of the casing taken across the line AA'. Figure 3 illustrates the improved method for cementing casing in a bore 5 position of the skirt during the cementing ophole. In accordance with the present invention, eration. a flexible sleeve or skirt is attached to the bottom Referring specifically to Figure l, .I ll designates of the casing. This sleeve is adapted to expand the bore hole into which is disposed casing H. against the bore hole wall as the sleeve is inflated A conventional shoe device I2 is attached to the with cement. bottom of casing II. In accordance with my in- The general technique for the recovery of crude vention, I attach to the outer surface of casing l l oil from oil-producing subterranean sands is well a skirt arrangement [3. Also in accordance with known. Generally, the process comprises drilling my process, I employ at least one closed breaka bore hole or well through non-producing subable opening in the lowerarea of easing ll. Usuterranean areas to oil-producing areas which ally a series of closed breakable openings are degenerally comprise oil-producing sands. After sirable in the lower area of casing H. Figure 1 the desired oil-producing area is reached, it is illustrates the arrangement of my device prior to the usual practice to cement the area between the the commencement of the cementation process. well casing and the bore hole wall. This proce- Figure 2 illustrates the lapping over or folding dure is followed in order to prevent the flow of of my expandable skirt device. Figure 3, as hereundesirable fluids into the oil-producing sand tofore pointed out, illustrates the operation of my area. The usual procedure is to introduce the device during the cementation process. In acrequired volume of cement as a slug in the drillcordance with my process at the surface I insert ing mud and to circulate the drilling mud. The a suitable plug l4 into the casing. In the area cement passes downwardly within the casing and above the plug I place the desired amount of ceupwardly between the casing and the bore hole ment which I intend to use in the cementation Wall to the desired area, at which time circulation process. I insert another plug [5 on top of the is discontinued. cement and fill the area above plug [-5 with drill- In this operation it is very diflicult to secure ing mud, and circulate the mud and the cement a satisfactory cementation of the desired area. within the casing to the bottom of the drill hole For example, the drilling mud apparently has an as shown in Figure 3. As the plug l4 approaches adverse effect upon the cement either prior to or the bottom of the casing, drilling mud within the during the setting period. One result of this is casing is forced out of the casing through shoe that the cement seems to form channels through [2 up into the area between the casing and the which undesirable fluids may flow into the oilbore hole Wall. When plug [4 reaches the bottom producing area, which fluids impair the efiiciency of the shoe it seals off further flow of material and production of the well. Another problem enthrough the shoe. Thus, the pressure within the countered is that it is very difficult to secure a casing is increased causin breakage of closed tight seal of cement against the bore hole Wall. breakable ports 25. It is to be understood that I have now discovered a procedure and appathese ports may be grooved or otherwise treated ratus which is particularly adapted and directed so as to make the tensile strength of them subtoward overcoming these problems heretofore stantially less than the strength of the casing encountered. My apparatus comprises a flexible, wall. I expandable sleeve or skirt device which is at- Upon breakage of ports 25 the sleeve or skirt tached to the lower end of the casing. In acarrangement I3 is caused to expand outwardly cordance with my process I force the cement into against the bore hole wall. My skirt arrangement this sleeve or skirt device and cause the device is so designed that initially the lowest portion of to progressively expand against the wall of the the skirt will be forced against the bore hole wall bore hole. During the setting period the cement and that an upward thrust against the drilling is not in direct contact with the drilling mud, mud fluid will be exerted as the skirt progressively thus assuring a better cementation result, and upwardly expands against the bore hole wall. My process and device may be readily under- A special adaptation of my process is to employ stood by reference to the drawings illustrating breakable straps l7, l8, l9 and 20'. It is to be one embodiment of the same. Figure 1 illustrates understood that the numberof these straps may the typical bore hole into which is disposed a casbe varied considerably, depending upon the height of the skirt and the distance between the casing hinged straps'or latches which can be flopped outwardly from the lower edge of the strap as the cement in the skirt rises. As the lower half of the strap is moved outwardly, the strap around the skirt holding it securely to the outer wall of the casing will be released.

My invention generally is concerned with the use of a sealed area in the bottom of the bore.

hole into which cement is forced'and into which drilling mud cannot seep during the cement setting period. It is also generally concerned with the use of this sealed area so as to cause the ce-,

ment to exert a tight seal against the borehole wall rather than to take the path of least resistance and flow upwardly into the area of the drilling mud. By operating in this manner, cavitationor channeling of'th e cement is prevented and a tight seal is secured in the area between the casing and the bore hole wall.

Although any suitable device may be used in order to carry out my process, the preferred method is to employ an expandable skirt device which is attached to the lower part of the casing; The expandable device is caused to expand by forcing cement through suitable openings .or ports in the casing into the area between the inner surface of the expandable device and the outer surface of the casing. A preferred device comprises a lapped unit, the lappings of which are suflicient to expand throughout the area it is desired to cement. The length of the skirt may vary appreciably. It may range, for example, from 50 to 100' or even as high as 1009 feet. Although it is desired to force the cement into the expandable device at the bottom of the device, it is to be understood that under certain conditions, particularly when the device is quite long, other points of entry for the cement may be provided for. Furthermore, although it is preferred that the expandable device comprise a suitable metallic material, it is to be also understood that other materials such as plastic, cloth, or various fabrics may also be utilized.

The process of my invention is not to be limited by any theory as to mode of operation, but only in and by the following claim in which it is desired to claim all novelty insofar as the prior art permits.

What is claimed is: ,Improved apparatus for cementing a casing in a .well bore comprising a casing section having at least on'e port through the wall thereof, a break- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,209,634 Sweet Dec. 19, 1916 1,684,551 Manning Sept. 18, 1928 1,687,424 Boynton Oct. 9, 1928 1,912,578 Halliburton June 6, 1933 2,275,936 Baker Mar. 10, 1942 2,357,145 Standefer Aug. 29, 1944 2,460,561 Winkelmann Feb. 1, 1949 

